Anders Behring Breivik, the right-wing extremist who killed 77 people in gun and bomb attacks in 2011, has sued the Norwegian government for human rights violations for keeping him imprisoned in isolation.

Here are five things to know about the case, which starts Tuesday in a gym-turned-courtroom in the prison where he is serving his sentence for terrorism and mass murder:

"INHUMAN" CONDITIONS

Breivik, 37, has sued the government for allegedly breaching articles on torture and the right to private and family life in the European Convention on Human Rights. Breivik says he's been subjected to "degrading" treatment with frequent strip searches and handcuffing. He also argues that it is "inhuman" to keep him isolated from other prisoners and to strictly control his mail correspondence and visitors.

GOVERNMENT REJECTS CLAIMS

The government says the conditions Breivik faces in prison are "well within" what's allowed under the European Convention on Human Rights. It says authorities are treating Breivik humanely and with dignity despite the severity of his crimes. It also says the restrictions he faces, including no contact with other prisoners, is for his own safety, that of prison staff and society at large.

HELD IN ISOLATION

Breivik is serving a 21-year sentence, which can be extended for the rest of his life, as the only inmate in a high-security section of Skien prison, a two-hour drive south of Oslo. He has three cells at his disposal: one where he sleeps, one where he studies and one where he exercises. He has a TV, PlayStation and a computer without Internet connection. He is also given daily access to an exercise yard. The government says he's recently been allowed to cook his own food. His mail correspondence is strictly controlled by prison officials to make sure he doesn't make contact with other right-wing extremists.

FOUR-DAY TRIAL

After opening arguments on Tuesday, Breivik is set to take the stand on Wednesday. Breivik has called two witnesses to testify: prison psychiatrist Randi Rosenqvist and Helga Fastrup Ervik from Norway's ombudsman against torture and ill-treatment. Government witnesses include officials and doctors from the two prisons where Breivik has been held since his arrest. Closing arguments are set for Friday. The court's verdict is expected a month later.

SURVIVORS STAYING AWAY

Survivors and families of victims are trying to ignore the trial, which some fear will reopen emotional wounds. Breivik was convicted in 2012 of terrorism and mass murder for a bombing in Oslo and shooting massacre on Utoya island on July 22, 2011. Some worry that he will try to use the case to bring attention to his extremist views. In a manifesto released just before the attacks, Breivik wrote that militant nationalist should use prison time to "consolidate and recruit patriotic resistance fighters."